(40r) Synthesis, Characterization and Application of Metal Organic Framework with One or Two Metal Sites for CO2 Adsorption
Crystalline metal-organic frameworks (MOFs) have recently emerged as potential candidate adsorbent for CO2 capture applications mainly due to their high surface area and tailorable structure. The presence of open metal sites in some MOFs strengthens their adsorption sites, which are favorable for CO2 capture and CO2 separation. The objective of this study is to compare the performance of five different MOFs for CO2 capture. Specifically, single metal (Mg, Co, and Zn-MOF-74 and Cu-MOF-199) and two metal (Mg-Co-MOF-74) MOFs were synthesized and characterized using X-ray diffraction (XRD) patterns, surface and bulk elemental analysis (XPS and CHN), scanning electron microscopy (SEM), CO2 adsorption isotherm. XRD and XPS showed that the structures of the samples were in a good agreement with previous reports and all metal cations were incorporated within the MOF structure. The XRD pattern for Mg-Co-MOF-74 was identical to that of single metal MOF74. Higher affinity was found for Mg-Co-MOF-74 compared to other MOFs, based on Henry’s law constant. CO2 adsorption capacity of 5.6, 4.0, 2.2, 4.9, and 6.4 mmol/g were obtained for Mg, Co, and Zn-MOF-74, Cu-MOF-199, and Mg-Co-MOF-74, respectively, indicating higher adsorption capacity of two metal MOF towards CO2 compared to single metal MOFs. The higher affinity and adsorption capacity of Mg-Co-MOF-74 suggests that it is the most favorable MOF, among the five tested MOFs, for CO2 capture application.